A process for disproportionating paraffinic hydrocarbons to yield products containing iso-paraffinic hydrocarbons

ABSTRACT

A process for disproportionating paraffinic hydrocarbons containing three to seven, four to five, carbon atoms in a hydrogen atmosphere to yield products containing iso-paraffinic hydrocarbons containing one more and hydrocarbons containing one less carbon fragment per molecule is disclosed. In the process, the paraffinic hydrocarbon is contacted in a hydrogen atmosphere at about 700* to 900* F. with a solid, acidic catalyst comprising a minor, catalytically effective amount of a platinum-group metal and containing a hydrogen or metal exchanged crystalline aluminosilicate having pores in the 8 to 15 A range and a mole ratio of silica-to-alumina of greater than about 2 to 1 and a solid oxide support. The catalyst can contain from about 1 up to about 85 weight percent of the crystalline aluminosilicate. A preferred oxide support is silica-alumina which can further contain a minor amount of alumina such as an activated alumina of the gamma family.

United States Patent Chloupek 1 June 6, 1972 [s 1 PROCESS FORDISPROPORTIONATING PARAFFINIC HYDROCARBONS TO YIELD PRODUCTS CONTAININGISO- PARAFFINIC HY DROCARBONS Frank J. Chloupek, South Holland, Ill.

Atlantic Richiield Company, New York, NY.

221 Filed: June 26,1970- [21] Appl.No.: 50,330

[72] inventor:

[73] Assignee:

3,046,317 7/1962 Myers ..260/676 Primary Examiner-,-Delbert E. GantzAssistant Examiner-J. Nelson Attorney-McLean, Morton and Boustead [57]ABSTRACT A process for disproportionating parafiinic hydrocarbonscontaining three to seven, four to five, carbon atoms in a hydrogenatmosphere to yield products containing iso-paraffinic hydrocarbonscontaining one more and hydrocarbons containing one less carbon fragmentper molecule is disclosed. In the process, the parafiinic hydrocarbon iscontacted in a hydrogen atmosphere at about 700 to 900 F. with a solid,acidic catalyst comprising a minor, catalytically effective amount of aplatinum-group metal and containing a hydrogen or metal exchangedcrystalline aluminosilicate having pores in the 8 to 15 A range and amole ratio of silica-to-alumina of greater than about 2 to l and a solidoxide support. The catalyst can contain from about 1 up to about 85weight percent of the crystalline aluminosilicate. A preferred oxidesupport is silica-alumina which can further contain a minor amount ofalumina such as an activated alumina of the gamma family.

13 Claims, No Drawings PROCESS FOR DISPROPORTIONATING PNIC HYDROCARBONSTO YIELD PRODUCTS CONTAINING ISO-PARAFFINIC HYDROCARBONS The presentinvention relates to a process for converting paraffin feedstocks intomore desirable gasoline range hydrocarbons. More particularly, thepresent invention relates to a process whereby parafiin hydrocarbons ofthree to seven, preferably four to five, carbon atoms aredisproportionated in a hydrogen atmosphere to yield a product containinghigher and lower molecular weight paraffins, in the presence of a solid,acidic catalyst containing a platinum-group metal and a crystallinealuminosilicate. Still more particularly, the present invention concernsa process whereby paraffin hydrocarbons of from three to seven,preferably four to five, carbon atoms are disproportionated in ahydrogen atmosphere to yield a product containing higher and lowermolecular weight paraffins which differ from the feedstock by theaddition or removal of one methylene (CH group. The products of highermolecular weight include isoparaffins as do the products of lowermolecular weight of at least four carbon atoms.

In general, paraffins are noted for resistance to the chemicalconversions and as a class are considered relatively unreactive with thelower molecular weight paraffins showing the greatest resistance toreactivity. Because of the lack of reactivity, paraffins, such aspropane, butane, pentane, and the like, have found limited utility inchemical reactions or chemical processing although some of theseparaffins can, for example, be cracked, isomerized, dehydrogenated, oralkylated, to produce more valuable products. For example, propane canbe cracked to provide ethylene, with the loss of a methane fragment ordehydrogenated to propylene, for utilization as an olefin in subsequenttransformations.

In general, the process of the present invention comprisesdisproportionating a paraffin hydrocarbon feed by contacting the feedwith a highly acidic, platinum-group metal, crystalline aluminosilicateand solid metal oxide containing catalyst, under relatively moderateconditions of elevated temperature and pressure in a hydrogenatmosphere, to provide a product containing paraffins of higher andlower molecular weight.

, According to the present process, paraffin hydrocarbon feedstockscontaining three to seven, preferably four to five, carbon atoms arereacted to provide iso-paraffin having one carbon atom more than thefeed and paraffin having one carbon atom less than the paraffinhydrocarbon feed. As an example, two moles of butane may be reacted toprovide one mole of propane and one mole of iso-pentane; pentane can bereacted to provide iso-butane and iso-hexane. By the present inventiveprocess, a paraffin hydrocarbon of limited utility can be reacted toprovide highly useful iso-paraffin products, particu larly iso-paraffinsboiling in the gasoline range and which are useful as fuels, solvents,and the like.

In the instant process, the paraffin hydrocarbon feed, i.e., havingthree to seven, preferably four to five, carbon atoms per mole, andwhich can be n-parafiinic, iso-paraffinic or mixtures of nandiso-paraffinic, is introduced into a reaction zone, which can be, forexample, a fixed bed catalytic reactor, where it is contacted in ahydrogen atmosphere with a solid, highly acidic platinum-group metalcrystalline aluminosilicate and solid metal oxide-containing catalyst atan elevated temperature and pressure. The temperature will generally bein the range of about 700 to 900 F., preferably about 750 to 850 F Thepressure will often be about 200 to 1,000 or more psig, but it ispreferable to utilize pressures from about 300 to 600 psig. The feed isconveniently contacted with the catalyst at weight hourly spacevelocities (WI-ISV) of about 1 to 10, preferably about 4 to 8. The WHSVcan be varied with the selection of the paraffin feed, the temperature,and the pressure, to give a high conversion level over an economicduration. The mole ratio of molecular hydrogen to parafiin hydrocarbonin the reaction zone is usually at least about 0.5:1 and may often varyfrom about 0.5 to 5:1, or more and preferably is about 1 to 2:1.

As a number of carbon atoms in the parafiin feed molecules increase,cracking is more likely to occur at a given temperature. In the instantprocess, cracking is an undesirable side reaction in direct conflictwith the production of higher molecular weight paraffin which is aprimary objective of the present invention. Cracking is also detrimentalto catalyst activity and life due to the formation of coke on thecatalyst. It is, therefore, desirable to operate the process of thepresent invention at temperatures which, while consonant with attaininghigh activity of the reaction and high conversion levels of the feed,are not substantially higher than necessary, in order to avoid excessivecracking. It is possible to operate the process at a temperature whereatdisproportionation occurs readily while little cracking takes place.Since cracking activity is favored at higher temperatures, thetemperature is, accordingly desirably maintained at the lower end of therange providing for disproportionation of a given feed, that is, at atemperature effective to avoid substantial or significant cracking ofthe feed. Since the reactivities of paraffin feeds vary with the numberof carbon atoms per molecule, the specific temperature desired, may, ofcourse, vary with the feed chosen. Generally, the fewer carbon atoms permolecule of the feed, the higher the temperature required to attainsatisfactory disproportionation activity, and the higher the temperaturewhich can be tolerated without significant cracking.

A second reaction of impact on the reaction of the present invention isisomerization since the catalysts used are relatively active for thisreaction. It has been found, however, that disproportionationselectivity is generally higher for branchedchain paraffin hydrocarbonsthan for n-paraffins, suggesting that it is the branched isomers whichdisproportionate and that in this invention an n-paraffin feed is firstisomerized to a branched-chain isomer which, in turn, disproportionates.

The paraffin hydrocarbon feedstock converted in the process of thepresent invention can be substantially a single paraffin such as butane,or can be a mixture of paraffins, such as butane and pentane. The feedcan be n-paraffins, iso-paraffins or a mixture of n-paraffins andiso-paraffins. The feed may be derived from petroleum fractions, such asare found in various petroleum refinery streams and can be separated inmore or less pure form. Desirably, large amounts of olefins are excludedfrom the feed and, preferably, the feed will contain not more than about5% by weight of olefins. Feeds essentially olefin-free are particularlydesirable. Among the paraffin hydrocarbons suited for the process of thepresent invention are propane, n-butane, isobutane, n-pentane,isopentane, 2,2- dimethyl propane, n-hexane, iso-hexane, nheptane andisoheptane.

The catalyst in the disproportionation reaction of this inventioncontains a minor, catalytically effective amount, e.g., about 0.01 to 5percent by weight of the total catalyst, preferably about 0.05 to 1percent, of one or more of the platinum group metals; and acatalytically effective amount, e.g., from about I to 85 percent byweight of the total catalyst, preferably from about 5 to 45 or evenweight percent, of a crystalline aluminosilicate having a mole ratio ofsilica-to-alumina of greater than 2:1, e.g., from about 2:1 to 12:1,preferably from about 4:1 to 6: 1; and a solid metal oxide support,e.g., one or more of the refractory metal oxides of the metals of GroupsII to IV of the periodic chart such as silica, alumina, titania,zirconia and magnesia or their mixtures. The support can further containminor amounts or other materials added to impart a particular propertyto the catalyst without being significantly deleterious in otherrespects. Such support is often at least about 10, e.g., about 10 to98.9 weight percent, preferably about 20 to 94.5 percent of thecatalyst. In many cases, the oxide support may be the major proportionof the catalyst.

The crystalline aluminosilicate of the catalyst can be either asynthetic or naturally occurring crystalline aluminosilicate having notmore than about 0.5 equivalents of alkali metal per gram atom ofaluminum in the crystalline aluminosilicate, and

pores having diameters of about 8 to 15 A, preferably about 10 to 14 A,as in the case of the faujasite type, Usually, with a particular sourceof material, the pores are of relatively uniform size. Thealuminosilicate particles may have an ultimate crystal size of about 0.5to 15 microns, preferably about 0.5 to 1.5 microns. Thesilica-to-alumina more ratio of the crystalline aluminosilicate isgreater than 2:1, and is usually not above about 12:1, preferably beingabout 4 to 6:1.

Crystalline aluminosilicates are available in a number of synthetic andnaturally occurring alkali metal forms. For example, sodium crystallinealuminosilicates often have a sodium oxide-to-alumina ratio of about 0.7to l.l:l. Synthetic crystalline aluminosilicates are ordinarily preparedin alkali metal form. The alkali metal serves as a catalyst poison inthe present invention and undue amounts should not be present in thecatalyst used in the disproportionation reaction. In the catalyst of thepresent invention, therefore, at least partial replacement of the alkalimetal by hydrogen or by a polyvalent metal cation is necessary toprovide less than about 0.5 equivalents of alkali metal per gram atom ofaluminum in the aluminosilicate.

The crystalline aluminosilicate component of the catalyst utilized inthe present invention can, for example, be prepared by base-exchangingthe alkali metal crystalline alumino-silicate by treatment with asolution characterized by a pH in excess of about 3, preferably by a pHin the range ofabout 4.5 to 10, and containing hydrogen or a hydrogenprecursor capable of replacing the alkali metal. After treating toeffect the exchange, the resultant base-exchanged material is washedfree of water-soluble material, and the base-exchanged material is driedand subjected to a thermal activating treatment. The alkali metalcontent of the finished crystalline aluminosilicate component of thecatalyst is often less than about 4, preferably less than about 1,weight percent. The alkali metal aluminosilicate may be calcined priorto base-exchange in an atmosphere which does not adversely affect thealuminosilicate, such as air, nitrogen, hydrogen, flue gas, helium, orother inert gas, at a temperature in the range of about 500 to l,500 F.

The base-exchange required to introduce the necessary cations is carriedout for an adequate period of time, a sufficient number of times, and atappropriate temperatures to effect replacement of at least about 50weight percent, preferably about 60 to 90 weight percent, of the alkalimetal originally contained in the aluminosilicate and to effectivelyreduce the alkali metal content ofthe resulting crystallinealuminosilicate component of the catalyst to below about 4 weightpercent, preferably below about 1 weight percent. Stated another way,the finished catalyst contains less than about 0.5, preferably about0.25, equivalents of alkali metal per gram atom aluminum in thealuminosilicate.

It is contemplated that various ionizable compounds of hydrogen,hydrogen ion precursors, e.g. ammonium ions and the like, or of metalssuch as silver, copper, mercury and polyvalent metals can be used. Thepreferred polyvalent metals to be associated with the crystallinealuminosilicate employed as the catalyst of the present invention arethe metals of Group IIA of the Periodic Table, e.g., magnesium andcalcium. Also particularly suitable are the rare earth metals, includingcerium. The metals can be used either singly or in combinations amongthemselves or with hydrogen ion precursors. Compounds are used in theexchange where the polyvalent metal or hydrogen precursor is present asa cation. Inorganic salts will usually be employed, although organicsalts, such as acetic and formate can also be used.

While water will ordinarily be the solvent in the baseexchange solutionsused, it is contemplated that other solvents, although generally lesspreferred, can be used. Thus, in addition to aqueous solutions,alcoholic solutions and the like of suitable compounds can be employedin producing the catalyst utilized in the present invention. It will beunderstood that the compounds employed for the base-exchange solutionundergo ionization in the particular solvent employed in thepreparation.

The concentration of the compound employed in the baseexchange solutioncan vary, depending on the nature of the particular compound, on thealkali metal crystalline aluminosilicate undergoing treatment, and onthe conditions under which the treatment is effected.

The temperature at which the base-exchange is effected may vary widely,generally ranging from room temperature to an elevated temperature belowthe boiling point of the treating solution. The volume of thebase-exchange solution employed may vary widely, although generally anexcess is employed and such excess is removed from contact with thecrystalline aluminosilicate after a suitable period of contact. The timeof contact between the base-exchange solution and the crystallinealuminosilicate in any instance, whether by a single or a plurality ofsuccessive contacts, is such as to effect displacement of the alkalimetal ions to an extent such that alkali metal content of the catalystafter base-exchange is satisfactorily reduced. It will be understoodthat such period of contact may vary, depending on the temperature ofthe solution, the nature of the crystalline aluminosilicate, and theparticular compound employed for the base-exchange. Thus, the period ofcontact may extend from a brief period on the order of a few hours forsmall particles to longer periods on the order of several days for largepellets.

After the base-exchange treatment, the crystalline aluminosilicatecomponent of the catalyst is removed from the treating solution.Superfluous materials, such as anions introduced as a result of thetreatment, are removed by waterwashing the treated composite. The washedproduct is then dried, generally in air, to remove substantially all thewater. While drying can be conducted at ambient temperatures, it isgenerally more satisfactory to facilitate the removal of moisture bymaintaining the material at a temperature between about 150 and 600 F.for about 4 to 48 hours.

The dried material is then subjected to an activating treatment,essential to establish the catalytic activity of the composition. Suchtreatment entails heating the dried material in an atmosphere which doesnot adversely affect the crystalline aluminosilicate component of thecatalyst, such as air, nitrogen, hydrogen, flue gases, helium, or otherinert gas. The dried material can be heated, in air for example, to atemperature in the approximate range of about 500 to 1,500 F. for aperiod of at least about 1 hour, and usually about one to 48 hours.

The active aluminosilicate component prepared in the foregoing mannercan be combined, dispersed or otherwise intimately admixed with thesupport in such proportions that the resulting product contains, forinstance, from about 1 to weight percent, preferably about 5 to 80weight percent, of the active aluminosilicate in the final composite.

The porous oxide support component of the catalyst is usually comprisedof a metal oxide or a mixture of metal oxides, the metals of which areoften selected from Groups ll to IV of the periodic chart. Examples ofsuch metal oxides are silica, alumina, titania, zirconia, magnesia andtheir mixtures. It is preferred that the catalyst base contain bothsilica and alumina in the oxide form of relatively high acidity. Thesupport can thus contain a major amount, of, for example, about 60 to 99weight percent, preferably 80 to 95 weight percent, of amorphoussilica-alumina. The support can further contain a minor amount of, forexample, 1 to 40 weight percent, preferably 5 to 15 weight percent ofalumina, especially an activated alumina of the gamma-alumina familysuch as gamma-, etaor chi-alumina. Minor amounts of other materials canalso be added to the support to impart a particular property to thecatalyst without being significantly deleterious in other respects.

A solid support advantageous for use in the catalyst of the presentinvention is an acidic, silica-based material, e.g. having a D Lactivity of at least about 20, preferably at least about 30 whendetermined according to the method of Birkhimer et al., A Bench ScaleTest Method for Evaluating Cracking Catalysts," Proceedings of theAmerican Petroleum Institute, Division of Refining, Vol. 27 (III), page(1947) and hereinafter referred to as Cat. A. The silica-based supportpreferably has a substantial surface area as determined by the BETnitrogen absorption procedure (JACS, Vol. 60, pp. 309 et seq. (1938).The surface area of the support can be at least about 50 square metersper gram, and surface areas are often up to about 500 or more m /gm,preferably about 150 to 400 m /gm. It is preferred that the catalystsupport be relatively dry to avoid undue reaction with and loss ofcatalytic promoting materials. Thus, it is advantageous that the supportbe calcined, e.g. at temperatures of about 600 to 1,500 E, or more, toreduce the water content, but such calcination should not be so severethat the support is no longer catalytically active.

The support component can contain other materials in addition to silicawhich materials, when combined with silica, provide an acidic materialas'in, for instance, the case of silicaalumina. Often these materialsare one or more oxides of the metals of Groups II, III and IV of thePeriodic Table. Examples of the composite contemplated herein under thegeneric designation of silica-based materials are often composedpredominately of or even to. a major extent of silica. These supportsinclude, for example, silica-alumina, silica-boria, silica-zirconia,silica-magnesia, silica-alumina-zirconia, silicaalumina-thoria,silica-alumina magnesia, and the like. The support often contains silicaand alumina and such supports, whether naturally-occurring as inacid-treated clays, or a synthetic gel, will frequently contain about to60, preferably about to 45, weight percent alumina. In addition, suchsilica-alumina supports can, and preferably do, contain a portion of thealumina as a separate, distinct phase.

A preferred catalyst support can be made by combining a silica-aluminahydrogel with a hydrous alumina. An advantageous hydrous aluminacomponent is, when analyzed by X-ray diffraction of dry samples, eitherone or a mixture of amorphous hydrous alumina and a monohydrate, e.g.,boehmite, of less than about 50 A, preferably less than about 40 A,crystallite size as determined by half-widthmeasurements of the (0,4, 1) X-ray diffraction line-calculated by the Debye-Scherrer equation.

The mixture of the catalyst precursor components can be dried, e.g., atabout 220 to 500 F., preferably about 800 to l,400 F to provide theactive catalyst support. During calcination, the separate hydrousalumina phase of the mixture is converted to a gamma form or othercatalytically active alumina.

In providing the preferred catalyst support precursor for drying, thecomponents can be combined in any suitable manner or order desired, andadvantageously, each of the components is in the mixture infinelydivided form, preferably the particles are principally less thanabout 300 mesh in size. The finely-divided material can have an averageparticle size of about 10 to 150 microns and can be used to make acatalyst of this particle size which can be employed in a fluidized bedtype of operation. However, if desired, the mixture of catalyst supportcomponents can be placed in macrosized form, that is, made intoparticles as by tabletting, extruding, etc., to sizes of the order ofabout one sixty-fourth inch to one-half inch or more in diameter andabout one thirty-second inch to 1 inch or more in length, before orafter drying or calcination. If the formation of the macrosizedparticles is subsequent to calcination and the calcined particles havebeen contacted with water, the material can be recalcined.

On a dry basis, the preferred supports of the catalyst of the presentinvention contain about 45 to 95 weight percent of the amorphouss'ilica'alumina xerogel and about 5 to weight percent of the separatelyadded alumina phase. The alumina content from the silica-alumina xerogeland the separate alumina phase is about 20 to 70 weight percent,preferably about 25 to weight percent, based on the dried support. Also,the catalyst support generally contains less than about 1.5 weightpercent, preferably less than about 0.5 weight percent, sodium.

The silica-alumina component of the precursor of the preferred catalystsupport of the present invention can be silica-alurnina hydrogel whichcontains about 55 to 90, preferably about 25to 35, weight percentalumina, on a dry basis. The silica-alumina can be naturally occurringor can be synthetically prepared by any desired method and severalprocedures are known in the art. For instance, an amorphoussilica-alumina hydrogel can be prepared by co-precipitation orsequential precipitation by either component being the initial materialwith at least the principal part of the silica or alumina being made inthe presence of a silica gel. It is preferred that the silica-aluminahydrogel be made by forming a silica hydrogel by precipitation fromalkali metal silicate solution and an acid such as sulfuric acid. Thealum solution may be added to the silica hydrogel slurry. The alumina isthen precipitated by raising the pH into the alkaline range by theaddition of an aqueous sodium aluminate solution or by the addition of abase such as ammonium hydroxide. Other techniques for preparing thesilica-alumina hydrogel are well known in the art, and these techniquesmay be used in the practice of the invention.

The alumina hydrogel which can be combined with the silica-alumina ismade separately from the silica-alumina. The alumina hydrogel may beprepared, for example, by precipitation of alumina at alkaline pH bymixing alum with sodium aluminate in an aqueous solution or with a basesuch as soda ash, ammonia, etc. As noted above, the alumina hydrogel canbe in the form of amorphous hydrous alumina or alumina monohydrate,e.g., of up to about 50 A crystallite size as determined by X-raydiffraction analysis. The amorphous hydrous alumina generally containsas much combined water as does an alumina monohydrate. Mixtures of themonohydrate and amorphous forms of hydrous alumina are preferred andoften this phase is composed of at least about 25 percent of each of theseparate members.

In preparing the catalyst, the solid metal oxide support material andcrystalline aluminosilicate can be intimately mixed together oralternatively, and particularly when the support contains two or moresolid metal oxide components, such as a mixture of silica-alumina andalumina, the silica-alumina and the alumina may be intimately mixed, forinstance, by colloidal milling. The crystalline aluminosilicate can beadded after the milling, and alternatively, this ingredient can also becombined before the colloidal milling operation. The mixture is dried,water washed to acceptable concentrations of, for instance, sodium, andredried in the preferred procedure. The drying, especially the initialdrying, is advantageously effected by spray drying to give microspheres.The combined materials can also be shaped as by extrusion into suitableshapes.

The dried catalyst support and crystalline aluminosilicate mixture canthen be contacted with an aqueous solution of a water solubleplatinum-group metal compound, such as chloroplatinic acid, toimpregnate the platinum-group metal compound into the support. Theimpregnated support can then be dried and heated to convert the compoundto the metal. Platinum is the preferred metal and chloroplatinic acid isthe preferred platinum compound.

The following examples further illustrate the process of this invention:

EXAMPLE I A platinum-metal containing catalyst is prepared by combining15 weight percent of a synthetic faujasite type, hydrogen-formcrystalline aluminosilicate substantially completely hydrogen-exchangedand having pores of about 13 A and a silica-to-alumina mole ratio ofabout 5 to l, with a support composed of about 75 weight percentamorphous silica-alumina, balance alumina. The catalyst materials areextruded into one-sixth inch in diameter cylinders and impregnated witha solution of chloroplatinic acid, dried and calcined. The catalystcontains about 0.5 weight percent platinum.

20 grams of the platinum-metal, crystalline aluminosilicatecontainingcatalyst is charged to a universal type reactor. Isobutane is introducedfrom a pressurized blow case. The conditions employed and the results ofthe analysis of the products appear in Table I.

TABLE 1 Run No. 1 2 3 6 Feed i-C i-C i-C i-C i-C WHSV 2.0 2.0 4.0 2.08.0 Temp. F. 750 850 850 850. 850 Press., psig 300 300 300 300 500 HIH'C 1 1 1 5 1 Conv. 46.55 54.73 47.73 63.77 51.81

Selectivities Disproportionation 30.48 26.55 25.58 24.59 31.81 L/H 1.5301.784 1.504 1.644 1.555 lsomerization 63.35 65.56 68.23 69.81 61.49Disproportionation and lsomerization 93.83 92.11 93.81 94.40 93.30

'H,/HC Hydrogen to hydrocarbon ratio. L/H light to heavy mole fraction C,/C,.

EXAMPLE 11 A platinum-metal containing catalyst is prepared by combining80 weight percent of the synthetic faujasite-type hydrogen-formcrystalline aluminosilicate of Example I with 20 weight percent ofalumina monohydrate. The catalyst materials are extruded intoone-sixteenth inch diameter cylinders and impregnated with a solution ofchloroplatinic acid, dried and calcined. The catalyst contains about 0.5weight percent platinum.

20 grams of the catalyst is charged to a Universal type reactor.Isobutane is introduced from a pressurized blow case. The conditionsemployed and the results of the analysis of the Two platinum-metal-,crystalline aluminosilicate-containing catalysts are prepared.

The first catalyst is prepared by combining 15 weight percent of asynthetic faujasite-type crystalline aluminosilicate having beensubstantially completely calcium-exchanged and having pore sizes ofabout 13 A and a silica-to-alumina mole ratio of about 5 to 1, with asupport composed of about 75 weight percent amorphous silica-alumina,balance alumina. The catalyst materials are extruded into one-sixteenthinch diameter cylinders and impregnated with a solution ofchloroplatinic acid, dried and calcined. The catalyst, hereinafterdesignated Cat. A, contains about 0.5 weight percent platinum.

The other catalyst is prepared by combining weight percent of thecalcium-exchanged crystalline aluminosilicate described above for Cat. Awith about 20 weight percent of alumina monohydrate. These catalystmaterials are also extruded into one-sixteenth inch diameter cylindersand impregnated with a solution of chloroplatinic acid, dried andcalcined. The catalyst, hereinafter designated as Cat. B, contains about0.5 weight percent platinum.

20 grams of each of Cat. A and Cat. B are charged to a Universal typereactor. Isobutane is introduced from a pressurized blow case. Thecatalysts are compared for average relative activity (Table 111), and acomparison of the isomerization and disproportionation activities atconstant conversion (Table IV). Tables V and VI also show the effects ofpressure and space velocity on the reaction. The conditions employed andresults of the analysis of products are listed below in Tables 111 toV1.

TABLE III Catalyst Cat. A Cat. B Feed i-C i-C WHSV 4 4 Temp., F. 850 850Press, psig 300 300 H /H'C 1 1 Average Relative Activity 2.14 2.65

TABLE IV Catalyst Cat. A Cat. 8 Feed i-C,, i-C. WHSV 4 4 Temp., F. 850850 Press, psig 500 500 H /HC 1 1 Conversion 65 65 SelectivitiesDisproportionation 32.27 27.45 lsomerization 46.98 58.58Disproportionation and lsomerization 79.25 86.03

TABLE V Catalyst Cat. A Cat. B Cat. A Cat. 8 Feed i-C i-C, i-C i-C WHSV4 4 4 4 Temp., F. 850 850 850 850 Press, psig 300 300 500 500 H /HC 1 11 1 Conversion 47.69 62.70 65.90 75.71

Selectivities Disproportionation 25.58 27.93 32.27 22.67 L/H 1.50 2.222.07 4.49 %1somerization 68.23 59.17 46.98 47.34 Disproportionation andlsomerization 93.81 87.10 79.25 70.01

TABLE VI Catalyst Cat. A Cat. B Cat. A Cat. B Feed i-C, i-C i-C i-C WHSV4 4 8 8 Temp., F. 850 850 850 850 Press, psig. 500 500 500 500 H /H'C ll l 1 Conversion 65.90 75.71 57.81 64.56

Selectivities Disproportionation 32.27 22.67 31.8l 27.45 L/l-l 2.07 4.491.56 2.34 Isomerization 46.98 47.34 61.49 58.58 Disproportionation andlsomerization 79.25 70.0l 93.30 86.03

it is claimed:

1. In the process for the disproportionation of feed paraffinhydrocarbon containing four to five carbon atoms per molecule to produceproduct isoparafiin hydrocarbon containing one more carbon atom permolecule than said feed paraffin hydrocarbon and product parafiincontaining one less carbon atom per molecule than said feed paraffinhydrocarbon, the improvement which comprises contacting said feedparaffin hydrocarbon in a hydrogen atmosphere at a temperature of fromabout 700 to 900 F. with a solid, acidic catalyst consisting essentiallyof a minor, catalytically effective amount of a platinum-group metal anda catalytically effective amount of a crystalline aluminosilicate havingless than about 0.5 equivalents of alkali metal per gram atom ofaluminum, a mole ratio of silica-to-alumina of greater than about 2:1and pores having diameters of about 8 to A, and at least about 10 weightpercent of solid metal oxide catalyst support comprising at least onerefractory metal oxide of the metals of Groups II to IV of the periodicchart.

2. The process of claim 1 wherein said contacting is conducted at atemperature of from about 750 to 850 F., and a pressure of from about200 to 1,000 psig.

3. The process of claim 1 wherein the catalyst contains from about 1 toweight percent of the crystalline aluminosilicate.

4. The process of claim 3 wherein the catalyst contains from about 0.05to 1 weight percent platinum and about 5 to 80 weight percent of thecrystalline aluminosilicate.

5. The process of claim 3 wherein the catalyst support contains fromabout 60 to 99 weight percent of amorphous silica alumina and from about1 to 40 weight percent activated alumma.

6. The process of claim 4 wherein the catalyst support contains fromabout 80 to weight percent of amorphous silica alumina and from about 5to 15 weight percent of activated alumina.

7. The process of claim 1 wherein the activated alumina is one of thegamma-alumina family.

8. The process of claim 5 wherein the activated alumina is one of thegamma-alumina family.

9. The process of claim 1 wherein said feed paraffin hydrocarboncomprises n-paraffins and isoparaffins.

10. The process of claim 3 wherein the catalyst support is aluminamonohydrate.

11. The process of claim 3 wherein said feed paraffin hydrocarbon isisobutane.

12. The process of claim 6 wherein said feed paraffin hydrocarbon isisobutane.

13. The process of claim 10 wherein said feed paraffin hydrocarbon isisobutane.

2. The process of claim 1 wherein said contacting is conducted at atemperature of from about 750* to 850* F., and a pressure of from about200 to 1,000 psig.
 3. The process of claim 1 wherein the catalystcontains from about 1 to 85 weight percent of the crystallinealuminosilicate.
 4. The process of claim 3 wherein the catalyst containsfrom about 0.05 to 1 weight percent platinum and about 5 to 80 weightpercent of the crystalline aluminosilicate.
 5. The process of claim 3wherein the catalyst support contains from about 60 to 99 weight percentof amorphous silica alumina and from about 1 to 40 weight percentactivated alumina.
 6. The process of claim 4 wherein the catalystsupport contains from about 80 to 95 weight percent of amorphous silicaalumina and from about 5 to 15 weight percent of activated alumina. 7.The process of claim 1 wherein the activated alumina is one of thegamma-alumina family.
 8. The process of claim 5 wherein the activatedalumina is one of the gamma-alumina family.
 9. The process of claim 1wherein said feed paraffin hydrocarbon comprises n-paraffins andisoparaffins.
 10. The process of claim 3 wherein the catalyst support isalumina monohydrate.
 11. The process of claim 3 wherein said feedparaffin hydrocarbon is isobutane.
 12. The process of claim 6 whereinsaid feed paraffin hydrocarbon is isobutane.
 13. The process of claim 10wherein said feed paraffin hydrocarbon is isobutane.